In concrete pumping applications, a common feature is the use of a multi-cylinder pump. A hydraulic actuator alternates piping between different cylinders. This configuration, though, does not lend itself to utilizing particular fittings that tightly seal the cylinders to the sections of piping. Moreover, it is well known that abrasive slurries are notorious for excessively wearing piping, fittings, and seals. Hence, when loose fitting seals, as with multi-cylinder pumps, are employed, the likelihood of both wear and failure dramatically increases because of the increased number of wearing surfaces.
One conventional solution is to employ a generally uniform hard seal or ring. The seal can be made of a variety of hard materials, such as tungsten carbide. Hard material can withstand a substantial amount of abuse from abrasive slurries. However, the hardness of the material generally results in a brittle material, one that is subject to fracture. Fractures can cause the seal to fail. Therefore, hard materials lack the inherent flexibility of softer materials, but are better equipped to withstand abrasion than softer materials.
Oftentimes, however, as a hydraulic actuator alternates piping between the different cylinders, the abrasive slurry is sheared. Typically, the shearing of the abrasive slurry, like concrete, causes stones and other abrasive components contained in the abrasive slurry to be sheared as well. Thus, by shearing the abrasive slurry, it is not uncommon to fracture very hard materials that provide seals between the sections of piping. However, if the hard materials are replaced with a softer material to avoid fracturing, then the good sealing properties of the harder materials can be lost.
Therefore, there is a need for a method and/or apparatus for efficiently sealing abutted pipes in abrasive and viscous fluid pumping applications that provides both a good seal and the ability to withstand the shearing of abrasive slurries.